1. Field of the Invention
The present invention relates to a lubrication system for a change gear transmission and, in particular, relates to a lubrication system for a change gear transmission wherein an oil reservoir is maintained separated from, preferably below, the transmission gearing to eliminate or minimize churn losses and lubricant is pumped through an easily accessible filter to necessary points for spraying of bearings and the like.
2. Description of the Prior Art
Change gear mechanical transmissions, i.e. transmissions utilizing positive jaw clutches to selectively engage and disengage selected gears to shafts, are well known in the prior art. Examples of such transmissions may be seen by reference to U.S. Pat. Nos. 4,805,471; 4,432,251 and 4,754,665, the disclosures of which are incorporated herein by reference. Lubrication of key points of such transmissions, especially the bearings, is critical to the life, capacity and performance of such transmissions, especially those transmissions intended for heavy duty vehicles. The prior art Transmissions typically include a lubricant sump in which a portion of the gearing constantly rotated for purposes of a splash and/or slinging type of lubrication system. The prior art also included pressurized lubrication systems wherein added pumps and/or the pumping action of bearings was utilized to supplement the splash/slinging lubrication systems, see U.S. Pat. Nos. 4,644,815; 4,914,968; 5,005,437 and 4,356,889, the disclosures of which are incorporated herein by reference.
The prior art transmissions, while very commercially successful, were not totally satisfactory as splash/sling lubrication systems may not provide sufficient lubrication/cooling under certain sever operating conditions, all lubricant was not continuously filtered, the combined churning and pumping losses were excessive and/or cleaning or replacing of the filter element was difficult.